1. Field of the Invention
The present invention relates to insufflation cannula assemblies adapted to receive an obturator, endoscope or other surgical instrument and more particularly, relates to a stabilizer assembly for providing support to instruments inserted within a cannula assembly while maintaining insufflation during insufflatory surgical procedures.
2. Description of the Related Art
In laparoscopic procedures, surgery is performed in the interior of the abdomen through a small incision; in endoscopic procedures surgery is performed in any hollow viscus of the body through narrow tubes or cannula inserted through a small entrance incision in the skin. Laparoscopic and endoscopic procedures generally require that any instrumentation inserted into the body be sealed, i.e. provisions must be made to ensure that gases do not enter or exit the body through the incision as, for example, in surgical procedures in which the surgical region is insufflated.
Insufflation involves filling a body cavity with a pressurized gas to maintain the cavity under a certain predetermined pressure. One way of performing the surgery is by first puncturing the skin in a desired body cavity region with a needle. The needle, commonly known as a Verres needle, includes a stylet which introduces an insufflation gas into the body cavity to inflate it.
A trocar assembly, comprised of a cannula assembly and an obturator, is then used to puncture the body cavity. Once the trocar assembly is properly inserted, the obturator may then be removed from the cannula assembly. This frees the lumen therein for the insertion of elongated endoscopes or instruments through the cannula to allow the surgeons to either view the anatomical cavity or perform surgical functions within the cavity, respectively.
Without the obturator to block the flow of insufflation gas out from the cavity, other means must be provided to maintain a relatively fluid-tight interface between the abdominal cavity and the outside atmosphere. Generally, there are two different sealing requirements for trocar cannulas. The first requirement is to provide a substantially fluid-tight seal when an instrument is not being introduced into or is not already present in the cannula. The second requirement is to provide a substantially fluid-tight seal when an instrument is being introduced into or is already present in the cannula.
An additional specification must be met in each of the two situations presented above. During a typical laparoscopic or endoscopic procedure, a single cannula, inserted in an incision, may be required at one point during the procedure to provide access to the surgical site for an instrument having a particular diameter. At other points during the surgery, the same cannula may be required to provide access for numerous other instruments each having a different diameter. This versatility is necessary because there is a limit to the number of cannulas which may be introduced through the skin to provide access to the insufflated cavity.
To meet the first sealing requirement, various types of cannula or trocar assemblies are provided with valves for maintaining a certain gas pressure in the cavity when no trocar or other surgical instrument is present in the cannula. These type of valves are generally effective for maintaining the pneumoperitoneum. For example, one form of cannula assembly incorporates a pivotally mounted flapper valve which is automatically opened upon insertion of an obturator or other instrumentation. Conventional flapper valves may also be manually opened by pivoting a lever provided on the exterior of the housing. An example of such a flapper valve is disclosed in U.S. Pat. No. 4,943,280 to Lander.
For the second sealing requirement, cannula assemblies have been developed which are provided with a series of resilient sealing elements having a central aperture, e.g., commonly assigned, co-pending applications Ser. No. 07/874,291 filed Apr. 24, 1992 and Ser. No. 07/873,416 filed Apr. 24, 1992. Upon insertion, an instrument passes through the sealing element and deforms the aperture so that a seal is maintained around the instrument.
Stretching of the seal element aperture may occur when an instrument is being manipulated by the surgeon. Since the seal elements must be resilient in order to accommodate different diameter instruments, manipulation causing lateral motion of the instrument with respect to the cannula housing will also stretch the apertures of the seal elements, again creating small openings for insufflation gases to escape.
Attempts have been made, by such seal assemblies as noted above, to provide a valve assembly which both accommodates instruments of different diameters and maintains the integrity of the seal between the body cavity and the atmosphere outside the patient's body. However, seal systems developed to date have failed to fully address the insufflation maintenance problem during the period when instruments are being inserted into or are already present in the cannula.
One solution to this problem would be to provide cannulas having more rigid sealing members which are capable of receiving instruments having the same diameter. This solution would not be very practical, however, because it would require far too many cannulas be inserted near the surgical site. For one reason, the cumulative minor gas losses from each cannula would defeat the very purpose of having such specifically designed cannulas. Another reason is that the advantages of minimally invasive surgery would be reduced. That is, the patient would have an increased number of trocar incision wounds which would lengthen the healing process. Additionally, the greater number of cannulas would complicate logistics during surgery, e.g., there would be a greater number of instruments to be monitored, thereby increasing, inter alia, the demands placed on the operating room personnel.
A need therefore exists for a valve assembly which may be incorporated into a cannula assembly or utilized in combination with any type of tubular member for providing access into the body of a patient, while permitting introduction of instruments, differing in diameter from one to the next, through the valve assembly into the body with reduced loss of insufflation gases.